Which normal waveform is typically NOT seen in the posterior leads?

The waveform that is typically not seen in the posterior leads is the wicket spike. Wicket spikes are characteristic of the temporal lobe activity, primarily observed in the anterior leads during an EEG recording. They are associated with normal brain activity in specific areas, particularly tied to the temporal lobes.

In contrast, the other waveforms mentioned are associated with posterior leads. The lambda wave, seen frequently in the occipital region, is indicative of visual processing. POSTS, or positive occipital theta bursts, are also expected in the posterior leads and occur during phases of relaxed wakefulness or light sleep. Photic driving, which is the brain's response to flashing lights, is generally recorded in the occipital region as well.

Thus, wicket spikes, being primarily temporal in their representation, do not typically appear in the posterior leads, highlighting their distinct localization related to brain function.